First chronological appearance of the Holodeck.
The Klingon battle cruiser that appeared in this episode was a reuse of the K't'inga class model.
The "mind reading" sequence makes mention of how Archer saved Trip's life in the Omega training mission, established in the previous episode, Strange New World (2001).
This episode suggests, indirectly and maybe inadvertently, the origin of the Klingon cloaking device.